Update go.mod and go.sum to latest version from networkservicemesh/cm…

…d-nsc-vpp@main

PR link: networkservicemesh/cmd-nsc-vpp#291

Commit: 4623f4b
Author: Network Service Mesh Bot
Date: 2021-11-08 00:01:27 -0600
Message:
  - Sync files with networkservicemesh/cmd-template
Signed-off-by: NSMBot <nsmbot@networkservicmesh.io>

apps/nsc-memif/nsc.yaml

@@ -17,7 +17,7 @@ spec:
     spec:
       containers:
         - name: nsc
-          image: ghcr.io/networkservicemesh/ci/cmd-nsc-vpp:cd40c89
+          image: ghcr.io/networkservicemesh/ci/cmd-nsc-vpp:4623f4b
           imagePullPolicy: IfNotPresent
           env:
             - name: NSM_REQUEST_TIMEOUT